Network-aware stream query processing in mobile ad-hoc networks

Abstract

Many real-time decision support and sensing applications can be expressed as continuous stream queries over time-varying data streams, following a data stream management model. We consider the problem of the efficient and resilient execution of continuous stream queries in tactical edge networks formed from mobile ad-hoc networks (MANETs) with limited backend connectivity. Previous approaches for distributed stream query execution target data center environments in which networks are static, and centralized control is feasible. The distributed, bandwidth-constrained and highly dynamic nature of MANETs render such approaches insufficient-while a stream query executes in a MANET, changes in the network topology mean that any fixed query plan eventually becomes outdated. We introduce an adaptive, network-aware approach for stream query planning in MANETs, which supports both single- and multi-input windowed stream query operators. The basic idea is to increase the path diversity available when executing stream queries by replicating query operators across many nodes in the MANET. During execution, it becomes possible to dynamically switch between different operator replicas based on connectivity and other network path conditions. We evaluate our approach in emulated MANETs, showing that it can increase substantially the robustness of distributed stream query processing under mobility.